Vertical axis wind turbine air concentration tower with reduced radar cross section

ABSTRACT

Disclosed is a vertical axis wind turbine air concentration tower with reduced radar cross section. The air concentration tower has a polygonal outer perimeter, a pivot located at each vertex of the polygonal outer perimeter, and an inwardly-positioned rudder blade operatively connected at each pivot. Each inwardly positioned rudder blade has a first wind-neutral position, and is pivotable through a plurality of angles that adjust based on an incoming wind direction, such that the incoming wind is channeled to the vertical axis wind turbine, which is located approximately at a center area of the polygonal outer perimeter. A radar absorbent material is applied to the vertical axis wind turbine air concentration tower to reduce the radar cross section. The air concentration tower is designed to provide higher wind speed to the vertical axis wind turbine than the surrounding ambient air.

CROSS-REFERENCE TO RELATED APPLICATION

The invention is related to and claims priority from co-pending U.S.Non-Provisional patent application Ser. No. 16/747,523 entitled AIRCONCENTRATION TOWER FOR WIND TURBINE to common inventor dos SantosRodrigues filed on Jan. 20, 2020, which is a Continuation in Part of andclaims priority from U.S. Non-Provisional patent application Ser. No.15/263,378 entitled VERTICAL WIND TURBINE filed on Sep. 13, 2016 also tocommon inventor dos Santos Rodrigues.

TECHNICAL FIELD

The present invention is generally related to a vertical axis windturbine (VAWT), and more particularly, is related to reducing radarcross section of the vertical axis wind turbines (VAWTs).

STATEMENT OF PROBLEMS ADDRESSED BY THIS INVENTION InterpretationConsiderations

This section describes technical field in detail and discusses problemsencountered in the technical field. Therefore, statements in the sectionare not to be construed as prior art.

Discussion of History of the Problem

Wind energy is one of the most cost-effective forms of renewable energy,with ever-increasing global installed capacity. For example, as of 2015Denmark, by percentage, generated 40% of its electric power from wind.

Wind turbines are generally categorized as horizontal axis wind turbines(HAWTs) or vertical axis wind turbines (VAWTs). A VAWT is moreefficient, simpler, and significantly cheaper to build and maintain thanan HAWT. VAWTs have other advantages, such as they always face the windthat enable the production of cheap and clean electricity. Furthermore,VAWTs do not require steering into the wind and have a large surfacearea for capturing wind energy. VAWTs can be installed at variouslocations, including roofs, highways, and parking lots. These produceless noise and can be scaled up from milliwatts to megawatts.

The demand for renewable energy is on the rise; as a result, there isincreasing focus on developing advanced models of VAWTs. The design of aconventional VAWT is complex, as the offset shaft is located outside theturbine axis. Furthermore, the offset shaft emerges from an independentshaft, resulting in unstable offset shaft operations.

Unfortunately, wind power remains stubbornly difficult to deploy. Forexample, a conventional VAWT has a relatively significant radar crosssection (RCS) and creates radar reflections large enough to interferewith the monitoring of aircraft near airports. If a region affected bythe VAWT is large enough, even known aircraft can be difficult todifferentiate as they fly over the VAWT, and detection of the aircraftmay be lost. Consequently, above mentioned event greatly decreases theability of the air traffic controller to maintain a safe operatingenvironment. Accordingly, VAWTs (indeed, all large wind turbines) areprohibited from being installed near airports or any other facilitiesthat rely on radar systems.

Accordingly, there exists a need for systems and features that reduceradar cross section for VAWTs. The present invention provides suchsystems, methods, devices and features.

SUMMARY OF THE INVENTION

According to the embodiments illustrated herein, a VAWT apparatus isprovided that concentrates air flow such that air reaching the VAWT isfaster than the ambient air surrounding the concentration tower. Theapparatus includes a fixed turbine axis, a plurality of carousal shafts,a plurality of carousal plates, a plurality of turbine blades, an offsetshaft assembly, a plurality of OTSs, a plurality of counterweights, anda plurality of timing and restricting shafts (TRSs).

The carousal shafts are operatively connected to the fixed turbine axis.The carousal plates are attached to the carousal shafts. The turbineblades are pivotally attached to the carousal plates. The plurality ofturbine blades includes one or multiple first turbine blades to receivewind, and one or more second turbine blades that are unexposed to wind.In one embodiment, the first turbine blade is exposed to a maximum areaby stretching away from the fixed turbine axis and the second turbineblade gets folded inside toward the fixed turbine axis.

In an aspect of the present invention, a vertical axis wind turbine airconcentration tower (VAWT ACT) with reduced radar cross section isprovided. The VAWT ACT includes a polygonal outer perimeter; a pivotlocated at each vertex of the polygonal outer perimeter; and a rudderblade mechanically linked to the pivot to oscillate based on an incomingwind direction wherein the rudder blade is inwardly-positioned having afirst wind-neutral position, and is pivotable through a plurality ofangles that adjust based on the incoming wind direction.

In this configuration of stacked modules, wind flow is channeled througheach of the plurality of single-modules. Each of the plurality ofsingle-modules comprises a vertical axis wind turbine. The plurality ofsingle-modules stack to channel wind flow through each module toincrease wind speed and power at each of the vertical axis wind turbine.The wind flow is channeled to each of VAWT located at a center area ofthe polygonal outer perimeter of each of the plurality ofsingle-modules. The center area has the vertical axis wind turbine witha fixed turbine axis. Each of the vertical axis wind turbine is anelliptical vertical axis wind turbine. Each of the vertical axis windturbine turns each generator. Preferably, up to four modules may bestacked. However, in certain applications more or fewer units may bedesirable.

Further, the VAWT ACT is coated with a radar-absorbent material toreduce the radar cross section. The radar-absorbent material comprisesat least one of carbonyl iron or ferrite, interspersed ferric compoundparticles, neoprene material, a urethane foam having conductive carbonblack, for example.

The polygonal outer perimeter is flat and angled in such a way thatradar beams falling at a large angle bounces off at a similar highreflected angle, thereby reducing the radar cross section. Incidentangles Σ (sigma) and θ (theta) at which the radar beams hit a particularportion of the air concentration tower are high when measured withreference to an imaginary axis XY. The incident angles Σ (sigma) and θ(theta) are between 90 degrees to 150 degrees with respect to theimaginary axis XY.

These features and advantages of the present disclosure may beappreciated by reviewing the following description of the presentdisclosure, along with the accompanying figures wherein like referencenumerals refer to like parts.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings illustrate the embodiments of systems,methods, and other aspects of the disclosure. A person with ordinaryskills in the art will appreciate that the illustrated elementboundaries (e.g., boxes, groups of boxes, or other shapes) in thefigures represent an example of the boundaries. In some examples, oneelement may be designed as multiple elements, or multiple elements maybe designed as one element. In some examples, an element shown as aninternal component of one element may be implemented as an externalcomponent in another, and vice versa. Furthermore, the elements may notbe drawn to scale.

Various embodiments will hereinafter be described in accordance with theappended drawings, which are provided to illustrate, not limit, thescope, wherein similar designations denote similar elements, and inwhich:

FIG. 1 illustrates a general view of the VAWT apparatus;

FIG. 2 illustrates an exploded view of the offset shaft assembly;

FIG. 3 illustrates the top view of the VAWT apparatus;

FIG. 4 illustrates an exploded view of the carousal plates;

FIG. 5 illustrates an exemplary view of the VAWT;

FIG. 6 illustrates a top view of an air concentration tower for avertical axis wind turbine;

FIG. 6 a illustrates the top view of the air concentration tower for thevertical axis wind turbine showing radar cross section mitigation;

FIG. 7 illustrates a side view of a single-module air concentrationtower for a vertical axis wind turbines; and

FIG. 8 illustrates a side view of a multiple-module air concentrationtower for vertical axis wind turbines.

DESCRIPTION OF AN EXEMPLARY PREFERRED EMBODIMENT InterpretationConsiderations

While reading this section (Description of An Exemplary PreferredEmbodiment, which describes the exemplary embodiment of the best mode ofthe invention, hereinafter referred to as “exemplary embodiment”), oneshould consider the exemplary embodiment as the best mode for practicingthe invention during filing of the patent in accordance with theinventor's belief. As a person with ordinary skills in the art mayrecognize substantially equivalent structures or substantiallyequivalent acts to achieve the same results in the same manner, or in adissimilar manner, the exemplary embodiment should not be interpreted aslimiting the invention to one embodiment.

The discussion of a species (or a specific item) invokes the genus (theclass of items) to which the species belongs as well as related speciesin this genus. Similarly, the recitation of a genus invokes the speciesknown in the art. Furthermore, as technology develops, numerousadditional alternatives to achieve an aspect of the invention may arise.Such advances are incorporated within their respective genus and shouldbe recognized as being functionally equivalent or structurallyequivalent to the aspect shown or described.

A function or an act should be interpreted as incorporating all modes ofperforming the function or act, unless otherwise explicitly stated.

The present disclosure is best understood with reference to the detailedfigures and description set forth herein. Various embodiments have beendiscussed with reference to the figures. However, those skilled in theart will readily appreciate that the detailed descriptions providedherein with respect to the figures are merely for explanatory purposes,as the methods and systems may extend beyond the described embodiments.For instance, the teachings presented and the needs of a particularapplication may yield multiple alternative and suitable approaches toimplement the functionality of any detail described herein. Therefore,any approach may extend beyond certain implementation choices in thefollowing embodiments.

References to “one embodiment”, “at least one embodiment”, “anembodiment”, “one example”, “an example”, “for example”, and so onindicate that the embodiment(s) or example(s) may include a particularfeature, structure, characteristic, property, element, or limitation,but not every embodiment or example necessarily includes that particularfeature, structure, characteristic, property, element, or limitation.Furthermore, repeated use of the phrase “in an embodiment” does notnecessarily refer to the same embodiment.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of the ordinaryskills in the art to which this invention belongs. Although any methodand material similar or equivalent to those described herein can also beused in the practice or testing of the present invention, the preferredmethods and materials have been described. All publications, patents,and patent applications mentioned herein are incorporated in theirentirety.

It is noted that as used herein and in the appended claims, the singularforms “a”, “and”, and “the” include plural referents, unless the contextclearly dictates otherwise. In the claims, the terms “first”, “second”,and so forth are to be interpreted merely as ordinal designations; theyshall not be limited in themselves. Furthermore, the use of exclusiveterminology such as “solely”, “only”, and the like in connection withthe recitation of any claim element is contemplated. It is alsocontemplated that any element indicated to be optional herein may bespecifically excluded from a given claim by way of a “negative”limitation. Finally, it is contemplated that any optional feature of theinventive variation(s) described herein may be set forth and claimedindependently or in combination with any one or more of the featuresdescribed herein.

All references cited herein, including publications, patentapplications, and patents, are hereby incorporated by reference to thesame extent as if each reference were individually and specificallyindicated to be incorporated by reference, and were set forth in itsentirety herein.

The recitation of ranges of values herein is merely intended to serve asa shorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein.

FIG. 1 illustrates a general view of apparatus 100, in accordance withat least one embodiment. Apparatus 100 includes a fixed turbine axis102, a plurality of carousal shafts (shown and explained in conjunctionwith FIG. 2 ), a plurality of carousal plates 104 a and 104 b, aplurality of turbine blades 106 (a-f), an offset shaft assembly (shownand explained in conjunction with FIG. 2 ), a plurality of offset timingshafts (shown and explained in conjunction with FIG. 2-3 ), a pluralityof counterweights (shown and explained in conjunction with FIG. 2 ), aplurality of timing and restricting shafts (shown and explained inconjunction with FIG. 3 ), and a generator (shown and explained inconjunction with FIG. 5 ). The carousal shafts (shown and explained inconjunction with FIG. 2 ) operatively connected to the fixed turbineaxis 102, and the carousal plates 104 a, and 104 b attached to thecarousal shafts (shown and explained in conjunction with FIG. 2 ).

The turbine blades 106 (a-f) pivotally attached to the carousal plates104 a, and 104 b. The turbine blades 106 (a-f) includes one or morefirst turbine blades to receive wind and one or more second turbineblades that are not exposed to wind. The one or more first turbineblades are exposed to a maximum area by stretching away from the fixedturbine axis. Further the one or more second turbine blades get foldedinside toward the fixed turbine axis.

The offset shaft assembly (shown and explained in conjunction with FIG.2 ) configured at a middle part of the fixed turbine axis 102. Theoffset shaft assembly (shown and explained in conjunction with FIG. 2 )includes an offset timing shaft (OTS), and a plurality of counterweights(shown and explained in conjunction with FIG. 2 ).

The offset timing shafts (OTSs) (shown and explained in conjunction withFIG. 2-3 ) suspended to the plurality of carousal shaft (202 a, and 202b). The OTS (shown and explained in conjunction with FIG. 2-3 ) isoffset from the center of the plurality of carousal plates 104 a and 104b and floats freely from the respective suspended carousal shaft (shownand explained in conjunction with FIG. 2 ) in order to reduce theaerodynamic drag.

The counterweights (shown and explained in conjunction with FIG. 2 )form a junction between the top carousal shaft 202 a and the bottomcarousal shaft 202 b. The plurality of timing and restricting shafts(TRSs) (shown and explained in conjunction with FIG. 3 ) emerge from theoffset timing shaft (shown and explained in conjunction with FIG. 2-3 )to connect with the plurality of turbine blades 106 (a-f) in order toexecute the operations of stretching away and folding inside. In analternative embodiment plurality of offset timing shaft (shown andexplained in conjunction with FIG. 2-3 ) may connected to the pluralityof TRSs (shown and explained in conjunction with FIG. 3 ).

FIG. 2 illustrates an exploded view of offset shaft assembly 200, inaccordance with at least one embodiment. A plurality of carousal shafts202 a and 202 b is operatively connected to the fixed turbine axis 102(shown in FIG. 1 ). The plurality of carousal shafts includes a topcarousal shaft 202 a and a bottom carousal shaft 202 b. The bottomcarousal shaft 202 b is coupled to the top carousal shaft 202 a. In oneembodiment, the top carousal shaft 202 a and the bottom carousal shaft202 b are mounted to central carousal plates 104 a and 104 b (shown inFIG. 1 ), located at the center of the carousal. Therefore, carousalplates 104 a and 104 b (shown in FIG. 1 ) are attached to the pluralityof carousal shafts 202 a and 202 b. The offset shaft assembly 200further includes a top counterweight 204 a and a bottom counterweight204 b to form a junction between the top carousal shaft 202 a and thebottom carousal shaft 202 b.

Turbine blades 106 a, 106 b, 106 c, 106 d, 106 e, and 106 f (shown inFIG. 1 ) are pivotally attached to the plurality of carousal plates 104a and 104 b. The plurality of turbine blades 106 (a-f) includes one ormore first turbine blades to receive wind. One or more second turbineblades are not exposed to wind. In one embodiment, the first turbineblade is exposed to a maximum area by stretching it away from the fixedturbine axis 102, and the second turbine blade gets folded inside towardthe fixed turbine axis 102. Offset shaft assembly 200 is configured atthe middle part of the fixed turbine axis 102 (shown in FIG. 1 ). Alsoshown in FIG. 2 , but described below, are radar absorbing elements ofRadar Absorbent Material (RAM), such as RAM 208.

Although RAM is shown as generally coating the surface of the ACT, wingsand wind turbine, preferably, RAM coats every radar-exposed surface ofan air concentration tower. Additionally, different types of RAM maycoat different surfaces to achieve performance characteristics such aswear versus radar-absorbing effectiveness versus weather resistance/heatresistance, for example.

FIG. 3 illustrates the top view 300 of apparatus 100, in accordance withat least one embodiment. Offset shaft assembly 200 (shown in FIG. 2 )includes an offset timing shaft (OTS) 302 suspended to carousal shaft202. In one embodiment, the OTS 302 is offset from the center of theplurality of carousal plates 104 a and 104 b. It floats freely from thesuspended carousal shaft 202, in order to reduce the aerodynamic drag.

The offset timing shaft (OTS) 302 is placed within the fixed turbineaxis 102. The plurality of OTS 302 is positioned in the direction of thefirst turbine blade exposed to wind. Offset shaft assembly 200 furtherincludes a plurality of counterweights 204 (shown in FIG. 2 ) to form ajunction between the top carousal shaft 202 a and the bottom carousalshaft 202 b. The plurality of counterweights 204 includes a topcounterweight 204 a and a bottom counterweight 204 b.

TRS 304 emerges from offset timing shaft 302 to connect with a pluralityof turbine blades 106 in order to execute the operations of stretchingaway and folding inside. In an embodiment the TRS 304 is preferablyconnected at the central region of the turbine blade 106, TRS 304controls the blade's opening and closing operations. TRS 304 for eachturbine blade 106 is connected to OTS 302. In an alternative embodimentTRS 304 is used to restrict the movement of the OTS 302 due to windforces being applied to the turbine blades 106 (a-f). Further in anotherembodiment the TRS 304 comprises two cylindrical tubes with shockabsorbing mechanism or sudden thrust dampener, which may reduce thesudden air blow associated damages. Furthermore, the TRS 304 isconnected with shaft alignment and synchronization control or feedbackloop in order to regulate axial movements of OTS 302.

Turbine blade 106 is modeled on an airplane wing, because in the presentVAWT, these blades function like an airplane wing. As wind hits theturbine blades, the blades will drive the top and bottom carousals toturn the generator (shown in FIG. 5 ). The blade creates a vacuum on thebackside of the turbine blade to increase the forward drive force.

FIG. 4 illustrates an exploded view 400 of carousal plates 104 a and 104b, in accordance with at least one embodiment. FIG. 4 is described inconjunction with FIG. 5 . FIG. 5 illustrates a side view 500 of a VAWT,in accordance with at least one embodiment. The top carousal plate 104 ais attached to the top carousal shaft 202 a. The bottom carousal plate104 b is attached to the bottom carousal shaft 202 b. The apparatus 100further includes a generator 502. In alternative embodiment, generatorcomprises six separate subunits which are connected to individualturbine blades to generate energy. The entire carousal assembly (104 and202) rotates in order to power the generator 502. The present carousalassembly (104 and 202) takes advantage of the additional rotationalspeed possible for offset shaft assembly 200 from the timing andrestricting shaft (304) of individual turbine blades 106, enhancing theeffect of the actual wind speed.

The plurality of turbine blades 106 (a-f) are hinged to top carousalshaft 202 a and bottom carousal shaft 202 b with a pin and bearingassembly, in order to receive wind and drive top carousal shaft 202 aand bottom shaft 202 b. In an alternative embodiment the pin and bearingassembly may also provide the pivotal movement to the top carousal shaft202 a and bottom carousal shaft 202 b. The apparatus 100 may include acontrol mechanism such as hydraulic, electric, or mechanical toorchestrate the closing and opening of the turbine blades 106 (a-f).Further the apparatus 100 may include sensing units to monitor themovement of the turbine blades 106 (a-f) and also measures the positionof the turbine blades 106 (a-f). Furthermore, the apparatus 100 may alsoinclude a diagnostic unit to autocorrect the opening and closingsequences of the turbine blades 106 (a-f). Additionally, the apparatus100 may include a transmitting unit to receive the sensed data from thesensing units and transmits the data to a remote monitoring unit. Theplurality of turbine blades 106 includes six turbine blades: 106 a, 106b, 106 c, 106 d, 106 e, and 106 f.

Generally, the turbine blades—106 a, 106 b, 106 c, 106 d, 106 e, and 106f are made of the fibre reinforced plastic (FRP) webs surrounded by twoFRP shells acting as aerodynamic fairings. FRP provides a lightweightstructure to the turbine blades 106 (a-f). The plurality of turbineblades 106 (a-f) are shaped to generate the maximum power from the wind.Primarily the design is driven by the aerodynamic requirements. Justlike an airplane wing, turbine blades 106 (a-f) operate by generatinglift due to the shape of the turbine blades 106 (a-f). The more curvedside generates low air pressures while high pressure air pushes on theother side of the aerofoil. The net result is a lift force perpendicularto the direction of flow of the air. In an embodiment the plurality ofturbine blades 106 (a-f) include corrugations to increase the stiffnessof the apparatus 100.

Apparatus 100 includes a generator 502, driven by top carousal shaft 202a and bottom carousal shaft 202 b. For example, top carousal plate 104 aturns a shaft that extends both above and below top carousal plates 104a, and 104 b. The shaft that extends below top carousal plate 104 a ismatted with top offset shaft assembly 200. The offset shaft assembly 200takes the center of the carousal and moves it to an offset position thatallows turbine blades 106 (a-f) to open to its maximum position.Alternatively, a control sequence regulates the opening and closing ofthe turbine blades 106 (a-f). Subsequently, counterweight 204 offsetsthe weight of open turbine blades 106, driving the VAWT. Bottom carouselplate 104 b also has a shaft extending through it, both above and belowthe plate. The shaft extending above the carousal plate is attached tothe bottom of the offset shaft assembly. The shaft extending below thebottom carousal plate drives the generator 502.

Thus, the present VAWT can be installed in various locations, such asroofs, highways, and parking lots. Furthermore, the present VAWTapparatus produces less noise and can be scaled from milliwatts tomegawatts. The present turbine has a simpler construction because theoffset shaft is located within the turbine axis. Also, thecounterweights of the present invention provide more stability to theoffset shaft operation.

The air concentration at the VAWT can be increased. According to theembodiments illustrated herein, an air concentration tower (ACT) forVAWT is provided, which is shown and explained in conjunction with FIG.6 , FIG. 7 and FIG. 8 .

FIG. 6 illustrates a top view of an air concentration tower for verticalaxis wind turbines, in accordance with at least one embodiment. The airconcentration tower for vertical axis wind turbine 600 comprises a fixedturbine axis 602, a polygonal outer perimeter (aka “circumference”) 604,a pivot 606 (also known in the art as a “link” or “joint”) located ateach vertex of the polygonal outer perimeter 604, a rudder blade 608 anda vertical axis wind turbine (VAWT) 610.

In an embodiment, the vertical axis wind turbine 610 is an ellipticalVAWT comprising a plurality of turbine blades 610 a (explained above indetail). The air concentration tower 600 channels airflow into the VAWT610.

The expression ‘polygonal outer perimeter’ or ‘polygon’ may beinterchangeably used without departing from the meaning and scope of thepresent invention.

The turbine illustrated in FIG. 6 has fixed turbine axis 602 (a centralaxis, i.e., an axis perpendicular to the ground about which the VAWT 610rotates to generate power). The pivot 606 located at each vertex of thepolygonal outer perimeter 604 is mechanically linked, and oscillates therudder blade 608 operatively connected to the pivot 606. Structurally,the pivot may be integrated with a top lip and a bottom lip (discussedbelow), or provided as a separate structural frame (not shown in theFigures). Each of the top lip and bottom lip comprise structure from theouter perimeter 604 to an interior perimeter. Accordingly, althoughstatic structures are illustrated for each pivot, it is readily apparentto those of ordinary skill in the art upon reading the disclosure thatother mechanical pivots, joints, or links may be used and achievesimilar results without departing from the scope and definition of theinvention, such as couplings and a connector rods, wheel-and-axis, orcylinder joints, for example.

The rudder blade 608 is an inwardly-positioned pivotable rudder, whichhas a first wind-neutral position, and is pivotable through a pluralityof angles that adjust based on the incoming wind direction, such thatthe incoming wind is channeled to the VAWT 610 located approximately atthe center area of the polygon 604.

The rudder blade 608 may be steady in the absence of wind, but in thepresence of airflow the rudder blade 608 adjusts itself according to thewind direction and channels the wind to the VAWT 610 to generate powerefficiently. The rudder blade 608 is designed so as to minimizeaerodynamic drag. In one embodiment, the rudder blade 608 may be a swingrudder blade, while in alternative embodiments it is a fixed rudderblade. Preferably, the rudder blade is made of fiber reinforced plastic(FRP), metal, composites, or any equivalent material which are readilyapparent to those of skill in the art.

Although a solid rudder blade that completely contours to the top lipand bottom lip is shown, it is readily apparent to those of ordinaryskill in the art upon reading the disclosure that a rudder blade mayhave cuts or shape that can enhance its performance, and so thesealternatives may be used and achieve similar results without departingfrom the scope of the invention.

In operation, the top lip and the bottom lip are preferably static, andallow each rudder blade to move therebetween. The air concentrationtower 600 further comprises at least one generator 702 (shown andexplained in conjunction with FIG. 7 and FIG. 8 ).

FIG. 7 illustrates a side view of a single-module air concentrationtower for vertical axis wind turbines mounted upon a pedestal. Thesingle-module air concentration tower 700 comprises a single-module 704having a fixed turbine axis 602, the polygonal outer perimeter 604, thepivot 606 located at each vertex of the polygonal outer perimeter 604,the rudder blade 608 and the vertical axis wind turbine (VAWT) 610 asalso described in FIG. 6 , where the VAWT 610 comprises the plurality ofturbine blades 610 a. The single-module 704 of the air concentrationtower 700 further comprises one or more generators 702.

From FIG. 7 one can see that the outer perimeter is defined by atrapezoidal top-lip that tapers from the outer perimeter to an interiorperimeter, and a trapezoidal bottom-lip that tapers from the outerperimeter to the interior perimeter. Further, each rudder blade islikewise trapezoidal and tapers from a maximum length along the outerperimeter to a smaller length at the interior perimeter. Although flatand trapezoidal sections are illustrated for the top lip and the bottomlip, it is readily apparent to those of ordinary skill in the art uponreading the disclosure that a continuous round (or oval) top lip or acontinuous round (or oval) bottom lip may be used and achieve similarresults.

The rudder blade 608 of the single-module 704 is inwardly-positioned,having a first wind-neutral position, and is pivotable through aplurality of discrete or continuous angles that adjust based on theincoming wind direction, such that the incoming wind is channeled to theVAWT 610 located approximately at the center area of the polygon 604. Inthe presence of the incoming wind, the rudder blade 608 of thesingle-module 704 starts adjusting itself in order to channel theincoming wind to the VAWT 610. Simultaneously, the incoming wind isforced to open the plurality of turbine blades 610 a of the VAWT 610 ofthe single-module 704 in order to turn on the one or more generators 702and to produce power by combining outputs of the one or more generators.

In one embodiment, each generator has, but is not limited to, 50 KWpower generation capacity provided through a 50 KW generator. The VAWT610 turns each generator 702 to produce power as in understood by thoseof ordinary skill in the power generation arts. In one embodiment, thesingle-module air concentration tower 700 comprises two generators 702(i.e., an upper generator and a lower generator). The upper and lowergenerators, each having a capacity of 50 KW, produce 100 KW by combiningthe outputs of the upper and lower generators. In yet anotheralternative embodiment, the single-module air concentration tower 700comprises more than two generators.

The single-module 704 of the air concentration tower 700 has thecapability of channeling the wind flow through the single-module 704 soas to increase the wind speed and thus the power output at the VAWT 610.The wind speed and power at the VAWT 610 can further be increased if aplurality of single-modules 704 are stacked up in a tower configuration800.

Accordingly, the present invention provides the ability to stack theplurality of single-modules 704 in the tower configuration 800. Theplurality of single-modules 704, once stacked up in the towerconfiguration, form and define a multiple-module air concentrationtower.

FIG. 8 illustrates a side view of a multiple-module air concentrationtower for vertical axis wind turbines (MMACT VWAT), in accordance withat least one embodiment. In an exemplary embodiment, the multiple-moduleair concentration tower comprises two single-modules 704. In analternative embodiment, the multiple-module air concentration tower mayhave more than two single-modules 704.

Each of the plurality of single-modules 704 comprises the fixed turbineaxis 602, the polygonal outer perimeter 604, the pivot 606 located ateach vertex of the polygonal outer perimeter 604, the rudder blade 608and the vertical axis wind turbine (VAWT) 610 as also described in FIG.6 and FIG. 7 . As previously discussed, the VAWT 610 comprises theplurality of turbine blades 610 a. The multiple-module air concentrationtower 800 further comprises at least one generator 702 in each of theplurality of single-modules 704.

The rudder blade 608 of each of the single-modules 704 isinwardly-positioned having a first wind-neutral position, and isdiscretely or continuously pivotable through a plurality of angles thatadjust based on the incoming wind direction, such that the incoming windis channeled to the VAWT 610 located approximately at the center area ofthe polygon 604. In the presence of the incoming wind, the rudder blade608 of each of the plurality of single-modules 704 adjusts itself inorder to channel the incoming wind to the VAWT 610 of each of theplurality of single-modules 704. Simultaneously, the incoming wind isforced to open the plurality of turbine blades 610 a of the VAWT 610 ineach of the plurality of single-modules 704 in order to turn thegenerator(s) 702. Therefore, air flow concentrates at the VAWT 610.

In one embodiment of the present invention, at least one generator has a50 KW power generation capacity. Of course, many generator sizes areknown and available in the arts and it is understood that any windgenerator may be incorporated into the invention simply by varying thesize and other parameters of the other components. These include, in KW:25, 100, 225, 300, 500, 600, 750, 1000, 1500, 1600, 2000, and 2500, forexample.

In a preferred embodiment of the invention the multiple-module airconcentration tower 800 comprises four generators 702, i.e., an uppergenerator and a lower generator in each of the single-modules 704. Theupper and lower generators of each of the plurality of single-modules704, preferably provides a capacity of 50 KW, to produce 200 KW bycombining the outputs of each generator.

In other words, each of the plurality of single-modules 704 forms a unitof 100 KW. Each of the plurality of single-modules 704 is stackable upto four units to provide a 400 KW capability from the air concentrationtower. In an exemplary embodiment, the air concentration tower comprisestwo single-modules 704 to provide a 200 KW capability from the airconcentration tower. In this way, the stacking up of the plurality ofsingle-modules 704 permits its practitioner to channel wind flow througheach of the plurality of single-modules 704 so as to increase the windspeed and power at each VAWT. Similarly, generators of other sizes maybe stacked to provide an array of desired power outputs.

In one embodiment of the present invention, the vertical axis windturbine, which is an elliptical vertical axis wind turbine (EVAWT) is 30feet in diameter. The generator 702 is 70 feet wide and 50 feet tall.The base of the air concentration tower is 90 feet and tapers to 70 feetat 100 feet, where the generator 702 is attached.

Likewise, these dimensions may scale. For example, in an alternativeembodiment of the invention, the vertical axis wind turbine (EVAWT) is 3feet in diameter. The base of the air concentration tower is 9 feet andtapers to 7 feet at 10 feet, where the generator 702 is attached.Similarly, here, the generator 702 is about 7 feet wide and about 5 feettall.

In embodiments, the air concentration tower has a shape and placed ororiented in such a way that reduces its radar cross section (RCS) as isdescribed below. Alternatively, the air concentration tower ismanipulatable into a shape and/or orientation that reduces its RCS.Additionally, the VAWT may also be shaped, oriented, or manipulated intoa shape or orientation that reduces its radar cross section. Of course,ideally both the air concentration tower and the VAWT are shaped, formedand placed or oriented in such a way that reduce the radar crosssection. In embodiments, these manipulations may be initiated remotelyand/or automatically in response to various radar operating conditions(or desired radar operating conditions).

According to various embodiments of the present invention, each rudderblade 608 is shaped to be RCS reducing. Additionally, the plurality ofturbine blades 610 a is shaped to be RCS reducing.

In other arts, it is appreciated that radar waves from a radar sourcetravel to an object and are then reflected by that object. Flat surfaceson that object that reflect incoming radar signals away from a radarreceiving station (typically co-located with the radar source) generatethe smallest received radar signal. Accordingly, in an embodiment, theair concentration tower has a cross-section with a perimeter of apolygonal shape, such as an hexagonal shape, having one corner of whichis oriented towards the radar source. Ideally, the top of the airconcentration tower also has flat surfaces, preferably formed astriangles that meet at a center point (in this case to form theappearance of a hexagonal pyramid).

Of course, other polygonal shapes are possible such as a quadrilateral,pentagon, heptagon, octagon, and the like, where each polygon has acorresponding top portion (tetrahedron, pentagonal pyramid, heptahedralor heptahedron, octagonal pyramid, and the like). These polygons may beregular (all sides having the same approximate length) or irregularand/or oblong.

Sometimes, multiple radars are present in an area. Additionally,sometimes a radar signal is generated at one location and received at asecond or third location. In these complex conditions, the airconcentration tower may have an oblong or unexpected shape (such as arhombus or trapezoid).

Referring back to FIG. 2 that shows the offset shaft assembly and FIG. 7that illustrates the side view of the single-module air concentrationtower for the vertical axis wind turbines. The components of the offsetshaft assembly and the air concentration tower are applied with a radarabsorbing/absorbent material (RAM) 208 that minimizes reflection ofradar beams by absorbing them. The RAM 208 may be applied to or attachedto one or more components of the offset shaft assembly, as well as tothe air concentration tower. In embodiments, the RAM 208 may be appliedin a webbed structure form. Additionally, the RAM may be applied in theform of a surface coating. The RAM 208 may be in the form of an ironball paint, a Jaumann, a carbon nanotube, or a split-ring resonator anda foam, for example. The RAM preferably comprises at least one ofcarbonyl iron or ferrite, interspersed ferric compound particles,neoprene material, or a urethane foam having conductive carbon black,for example.

Each rudder 608 may also be coated or covered on each side with the RAM,and is also mechanically limited to prevent any rudder 608 frompresenting a flat surface to a radar source (and, alternative, avoidingpresenting a reflective surface that would direct radar waves towards aknown radar-receiver).

In embodiments, it may be desirable to have the RAM coupled only tothose surfaces of the VAWT and ACT that face nearby radar source(s).Accordingly, in embodiments, those exterior surfaces of the ACT and VAWTthat face a radar source are substantially covered or coated with theRAM.

The RAM preferably coats or is attached to the entirety of the surfacesthat may face a radar source. However, it is appreciated that due tomechanical wear, and/or for smoother mechanical operation, it may bedesirable in some embodiments to coat or cover substantially theentirety of the surfaces while allowing portions of surfaces that aresubject to mechanical wear or which require lubrication to go uncoatedand/or uncovered.

In addition to the application of the RAM that absorbs the radar beamsand reduces the radar cross section, the air concentration tower isfurther structured to be almost flat and oriented to deflect theincoming radar beams (shown by arrows in FIG. 6 a ). The flat andproperly-oriented (here shown as a corner-orientation) air concentrationtower causes radar beams to reflect at angles that then bounce off awayfrom the radar collectors/receivers. Shown in FIG. 6 a , a preferred ACThas a polygonal/hexagonal cross-sectional shape, with sharpvertex/corners/edges that avoid reflecting the radar beams back to thesource/receiver/collector, but instead directs these radar waves intospace away from any collector/receiver, thereby reducing its radar crosssection.

Due to the sharp vertex/corners/edges of the ACT as explained above,angles (incident angles Σ (sigma) and θ (theta)) at which the radarbeams hit a particular portion of the ACT are high when measured withreference to an imaginary axis XY as shown in FIG. 6 a . In embodiments,the incident angles Σ (sigma) and θ (theta) are between 90 degrees to150 degrees with respect to the imaginary axis XY. Preferably, as in theillustrated embodiment, the incident angles Σ (sigma) and θ (theta) areeach 120 degrees with respect to the imaginary axis XY.

In regular polygons, Σ (sigma) and θ (theta) are equal, and subject tothe well-understood limitation that exterior angels of regular polygonsalways sum to 360-degrees. However, in irregular polygonalconfigurations, Σ (sigma) and θ (theta) may be different. Preferredangles of Σ (sigma) and/or θ (theta) include: 100 degrees, 135 degrees,and 160 degrees, for example (however, preferably do not present at ornear 90 degrees, which would likely reflect radar waves back in thedirection of the transmitter, and likely receiver location).

Because the surfaces of the ACT are generally and preferably flat, theangles of incidence of the radar source incoming to each surface, willbe the same as the angles of reflection of the radar waves and thusorient reflected radar waves away from the radar source(s).

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. There isno intention to limit the invention to the specific form or formsenclosed. On the contrary, the intention is to cover all modifications,alternative constructions, and equivalents falling within the spirit andscope of the invention, as defined in the appended claims. Thus, it isintended that the present invention cover the modifications andvariations of this invention, provided they are within the scope of theappended claims and their equivalents. No language in the specificationshould be construed as indicating any non-claimed element as essentialto the practice of the invention.

What is claimed is:
 1. A vertical axis wind turbine air concentrationtower with reduced radar cross section, comprising: a polygonal outerperimeter; a pivot located at each vertex of the polygonal outerperimeter; a rudder blade mechanically linked to the pivot to changeposition based on an incoming wind direction, the rudder blade beinginwardly-positioned, having a first wind-neutral position, and ispivotable through a plurality of angles; and a radar absorbent materialcoupled to an exterior surface of the vertical axis wind turbine airconcentration tower.
 2. The device of claim 1 wherein the polygonalouter perimeter comprises a plurality of flat surfaces, where each flatsurface is angled to reflect incoming radar waves away from a knownradar receiver.
 3. The device of claim 2 further comprising a verticalaxis wind turbine, the vertical axis wind turbine having radar absorbentmaterial coupled thereto.
 4. The device of claim 2, wherein an XY axisis defined by a line that bisects a corner that that is most orientedtowards the radar source, defining an angle sigma as an angle defined bythe XY axis and an exterior surface that faces away from a radar sourceto the left of an incoming radar wave, defining an angle theta as anangle defined by the XY axis and an exterior surface that faces awayfrom a radar source to the right of an incoming radar wave, the angles Σ(sigma) and θ (theta) are between 95 degrees to 150 degrees.
 5. Thedevice of claim 4 wherein the angles Σ (sigma) and θ (theta) are each120 degrees.
 6. The device of claim 1 wherein the radar absorbentmaterial comprises at least one of carbonyl iron or ferrite,interspersed ferric compound particles, neoprene material, or a urethanefoam having conductive carbon black.
 7. The device of claim 3 wherein arudder blade is configured to channel incoming wind to the vertical axiswind turbine located at a center area of the polygonal outer perimeter.8. The device of claim 7 wherein the vertical axis wind turbinecomprises a plurality of wings, and the wings are coated with a radarabsorbent material.
 9. The device of claim 7 the radar absorbentmaterial is a carbonyl iron.
 10. The device of claim 7 wherein thevertical axis wind turbine is an elliptical vertical axis wind turbine.11. The device of claim 7 further comprising an energy storage devicebeing coupled to the vertical axis wind turbine.
 12. The device of claim7 wherein the vertical axis wind turbine comprises an offset-turbineaxis.